From adb06b73f478afc3aa9175137f36155bf729db6a Mon Sep 17 00:00:00 2001
From: Douglas Anderson <dianders@chromium.org>
Date: Wed, 14 Jul 2021 09:33:50 -0700
Subject: drm/panel-simple: Power the panel when probing DP AUX backlight
Git-commit: 5ead9b5b157518520dd68b437f6d3640cefe608e
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

When I tried booting up a device that needed the DP AUX backlight, I
found an error in the logs:
  panel-simple-dp-aux: probe of aux-ti_sn65dsi86.aux.0 failed with error -110

The aux transfers were failing because the panel wasn't powered. Just
like when reading the EDID we need to power the panel when trying to
talk to it. Add the needed pm_runtime calls.

After I do this I can successfully probe the panel and adjust the
backlight on my board.

Fixes: bfd451403d70 ("drm/panel-simple: Support DP AUX backlight")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210714093334.1.Idb41f87e5abae4aee0705db7458b0097fc50e7ab@changeid
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/panel/panel-simple.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 4d7247d25f01..461794ae4188 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -827,7 +827,10 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc,
 		goto disable_pm_runtime;
 
 	if (!panel->base.backlight && panel->aux) {
+		pm_runtime_get_sync(dev);
 		err = drm_panel_dp_aux_backlight(&panel->base, panel->aux);
+		pm_runtime_mark_last_busy(dev);
+		pm_runtime_put_autosuspend(dev);
 		if (err)
 			goto disable_pm_runtime;
 	}
-- 
2.38.1